Latest TCS Aptitude Question SOLUTION: What is the unit’s digit in the number got from the following operation: (23)10 3 9 7 1 8

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What is the unit’s digit in the number got from the following operation: (23)10
3
9
7
1
8

Asked In TCS Sinji (6 years ago)

Unsolved Read Solution (11)

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Read Solution (11) :

heena sharma  (6 years ago)

unit digit 3 has cyclicity 4
10/4=remainder is 2
hence 3^2=9

Is this solution Helpfull? Yes (13) | No   

Ankit Yadav  (6 years ago)

first its not ankith its ankit...............apply the process of unit digit finding as it is 23^10.
now break it in the power of ((23)^4)^2 *23^2
[ (..3)*(..3)*(..3)*(..3)]^2 *[(..3)*(..3)]
[(..9)*(..9)]^2 *[..9]
[(..81)^2]*(..9)
(..1)^2 *(..9)
(...1) *(..9)=9
answer is 9

you can verify by using 23^10 on calculator

Is this solution Helpfull? Yes (7) | No   

AKHIL GUPTA  (6 years ago)

cyclicity of 3 is 4. when we divide 10 by 4, it is 2. 3^2 is 9. So, ans is 9

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ramakrishnan  (6 years ago)

9
coz 3^0=1, 3^1=3, and this goes on and we get 3^10 as 9(in the unit digit)

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NADIMPALLI SATISH BABU  (6 years ago)

Ans:-3
The last digit in lower value

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Ankit Yadav  (6 years ago)

9 will be the answer

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Pavithra  (6 years ago)

hi ankith can u explain how it is 9

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Ranjan Kumar  (6 years ago)

10÷4=remainder =2 now 3^2=9 hence unit digit is 9

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NANDEESWAR  (6 years ago)

We want to find the unit digit of 23 power 10
Now
consider 3 in 23

3*1=3is the unit digit in the same way
3*3=9
9*3=7
7*3=1
1*3=3(again 3 unit digit repeated)
so for power 4 we get 3 as unit digit
They have asked power 10
so, 10-8=2
so power 2 gives 9 as the unit digit

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Hema B  (6 years ago)

check whether the power value is fourth multiple.... 10 is not a 4th multiple..so take 4th multiple closest to 10.. 8 is a 4th multiple..reminder is 2. then 23^8 * 23^2 . for the power 4th multiple ...if the number is odd number , ans is 1 (is the number's power is 4th multiple). and we know that 9 is a unit digit for 23^2 .. so

23^8 *23^2= > (1)*(9) = 9 is an answer (unit dig)

another examples -
1) 13^36 = 1 ( 36 is multiple of 4 so 1 is a unit dig if the no is odd , 6 is a unit dig if a no is even )
2) 56^19 = 56^16 * 56 ^2 = (6) * (6) = 6

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M.sharath kumar reddy  (6 years ago)

3^10 =59049 unitdigit is 9

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